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< title > Enable DNSBL service in Postfix to reduce spam< / title >
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// < a href = "./index.html" > Document Index< / a > < / div > < h1 id = "enable-dnsbl-service-in-postfix-to-reduce-spam" > Enable DNSBL service in Postfix to reduce spam< / h1 >
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< div class = "admonition attention" >
< p class = "admonition-title" > Attention< / p >
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< p > If you're running a high-traffic mail server, you'd better setup a local
DNS server to cache DNS queries, because free RBL services like
< code > zen.spamhaus.org< / code > may improperly reply if your server exceed the DNS
query limit. Also, mail service higly relies on DNS queries, so a local
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DNS server speeds up the mail flow.< / p >
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< p > You can enable additional DNSBL services in Postfix to reduce spam. We use
< code > zen.spamhaus.org< / code > for example below.< / p >
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< li > Open Postfix config file < code > /etc/postfix/main.cf< / code > or
< code > /usr/local/etc/postfix/main.cf< / code > (on FreeBSD), append
< code > reject_rbl_client zen.spamhaus.org< / code > to parameter < code > smtpd_recipient_restrictions< / code > .
Final setting looks like below:< / li >
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< pre > < code > smtpd_recipient_restrictions =
...
reject_unauth_destination
reject_rbl_client zen.spamhaus.org
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< / code > < / pre >
< p > It must be placed after < code > reject_unauth_destination< / code > . You can add more DNSBL
services after < code > reject_unauth_destination< / code > , and they will be queried in the
specified order.< / p >
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< li > Restart or reload Postfix service is required.< / li >
< / ul >
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< div class = "admonition note" >
< p class = "admonition-title" > Another popular DNSBL server< / p >
< p > Another popular DNSBL server address is < code > b.barracudacentral.org< / code > . For more
details, please read its web site:
< a href = "http://www.barracudacentral.org/rbl" > Barracuda Reputation Block List (BRBL)< / a > < / p >
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< h2 id = "see-also" > See also< / h2 >
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< li > < a href = "./enable.postscreen.html" > Enable postscreen service< / a > < / li >
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< h2 id = "references" > References< / h2 >
< ul >
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< li > < a href = "http://www.postfix.org/postconf.5.html#reject_rbl_client" > Postfix Configuration Parameters: reject_rbl_client< / a > < / li >
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< li >
< p > < a href = "http://www.spamhaus.org" > Spamhaus website< / a > < / p >
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< li > < a href = "https://www.spamhaus.org/organization/dnsblusage/" > Spamhaus DNSBL Usage Terms< / a > < / li >
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< p style = "text-align: center; color: grey;" > All documents are available in < a href = "https://bitbucket.org/zhb/iredmail-docs/src" > BitBucket repository< / a > , and published under < a href = "http://creativecommons.org/licenses/by-nd/3.0/us/" target = "_blank" > Creative Commons< / a > license. You can < a href = "https://bitbucket.org/zhb/iredmail-docs/get/tip.tar.bz2" > download the latest version< / a > for offline reading. If you found something wrong, please do < a href = "http://www.iredmail.org/contact.html" > contact us< / a > to fix it.< / p >
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